cylinder head comp

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 1 Jul 2010, 4:52 pm

#788068

pumping up compression ratio........... been told to take 60thou out of a stock head to get it going what u think thats a long way on a normal egine

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 1 Jul 2010, 7:11 pm

#788101

You need to measure it up.

What engine size and have the heads been cut before?

What cam is in it so you know what compression to aim for?

What carbs are you running?

What fuel do you want to run?

What is the engine used for?

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 1 Jul 2010, 7:27 pm

#788114

so ill need to cc the head..... engine size 1640, kadrons, 98 octane,110 cam
cheers stevo

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 1 Jul 2010, 7:30 pm

#788115

Cool

What sort of car?

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 1 Jul 2010, 7:31 pm

#788116

manx

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 · 1 Jul 2010, 7:42 pm

#788121

you will be able to run 11:1 on that fuel but you probable need to run slightly richer and more retarded timing to ensure that it wont over heat. 10.5:1 would be safer idea.
yeah first work out the combustion cc and you deck cc.

10.5:1 on a 1640 would be a sum of 39~ cc deck+comb camber volume.

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 1 Jul 2010, 7:46 pm

#788124

Ok, so now we have gearing and use considerations, but generally with the Kaddies, I'd be keeping it under 8.0:1, preferebly about 7.8:1 but that can be fine tuned as you check out the heads and chambers.

You need to measure deck height and chamber volume to work out where it is now.

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 1 Jul 2010, 7:52 pm

#788133

okay cool but do u think 60thou is alot and that was from a very respectable vw fella

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 1 Jul 2010, 8:01 pm

#788139

I don't think he's respectable in telling you that.

Have the heads had any cut before?
Answer...noone knows...measure the chamber volume.

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 1 Jul 2010, 8:14 pm

#788142

thanks matt ur a champ ill be doing some measuring then ............... by any chance do you know what a respectable rwhp from a 1640cc is ................

Craig Torrens 6 times Australian, 7 times State Hillclimb Class Champion

8,040 posts · joined Jan 2003 · 1 Jul 2010, 8:16 pm

#788143

you say you have "stock" heads, but are they 040,043,113's ?

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 1 Jul 2010, 8:18 pm

#788144

040

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 1 Jul 2010, 10:21 pm

#788164

mmmmm
I dynoed a 1915 with dual 40 IDF's and 4-1 exhaust and stock 040's recently...it had 50rwhp.
Craig's 1915 makes 138rwhp.

It's too hard to say, but hp figures aren't everything.
I recently upgraded a 1641 with stock cam. Upgrade was 040 with 40 x 35.5 ported heads with reworked chambers and a set of 36 Dells and in a kombi camper, it now puts a smile on your face 🙂.

If your after a bit of a liven up, get the heads tidied up or even bigger valves too, this is the area that makes an engine perform well.

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

Craig Torrens 6 times Australian, 7 times State Hillclimb Class Champion

8,040 posts · joined Jan 2003 · 1 Jul 2010, 10:38 pm

#788168

bugzla wrote:040

ok thats good, they have the best casting of all the vw factory heads which allows more to be removed from the chambers.

like Matt said, I wouldn't get bogged down re HP figures........just build the best you can with what you have.

I had a great 1640 some 20 years ago, it had a 37/68 cam, twin Kadrons and compression was 8.5:1 with standard 040's......it had no problems at beating 6 cylinder holdens and fords of that era.....and it was probably only 60hpatw.

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 2 Jul 2010, 6:54 am

#788201

thanks guys ur a real help ill be looking into the 40mm inlet valves also when the head is apart might as well could be a b day present for my self in a couple of weeks ............................... no more socks for me and woolies vouches cause i dont think the machine shop will take them 😂

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 2 Jul 2010, 9:22 am

#788216

You should inquire about, 40mm inlet valves and seats, 35.5mm exvalves and seats, and a performance angle valve job. Then there's porting and chambers for the best package 🙂. Beware of a non volksie shop, they can often do questionable work if they are not up to speed with air cooled alloy heads.

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

bugzla Custom Title Time!

1,164 posts · joined Jun 2007 · 2 Jul 2010, 2:16 pm

#788264

looks like im sending south no vw places up here ................. bugger